The present invention relates to a surface treating and/or coating method for a molded article comprising a thermoplastic resin composition. More particularly, the present invention is concerned with a surface treating and/or coating method for a composition obtained by dynamically heat-treating a thermoplastic resin and/or a rubbery substance in the presence of a crosslinking agent, or a composition comprising the said composition and an inorganic filler incorporated therein, the said composition or the inorganic filler-incorporated composition being superior in the balance of rigidity, impact resistance, heat resistance, dimensional stability and moldability.
Heretofor, thermoplastic resins such as polyolefin resins, e.g. polyethylene and polypropylene, and polyester resins, have been used in various fields, including automobile parts, household electric products and electronic devices. In order to enhance the added value of these products there have been conducted surface coating, printing or plating, or lamination tehreto of non-woven fabric, foam or leather, or implantation of feathers therein. However, since polyolefin resins and polyester resins do not have a polar group, it is difficult to apply coating, bonding or printing thereto.
Generally, for the purpose of improving the coatability of the aforementioned products, there are conducted surface treatments such as a physical treatment, e.g. sandblasting, flame treating, corona discharge, or treatment using plasma, and a chemical treatment, e.g. treatment using chromic acid mixture or solvent.
However, such conventional physical treating methods involves the following problems: 1 the effect is unsatisfactory, 2 the treating speed is low and treating time long, 3 the apparatus is large-scaled and the process is complicated, and 4 the method is not economical.
The aforementioned chemical methods also involves problems; for example, 1 environmental pollution, and 2 considerable time, labor and cost are required for the disposal of liquid wastes used such as chemicals and solvents.
Both such conventional methods involve the problem that the coatability, printability and adhesive property in the use of coating material, ink and adhesive are still unsatisfactory.